[Objective] The temporal and spatial variation characteristics and the factors affecting the water conservation function in Gansu Province were studied to provide a reference and basis for regional water resources management decision-making and water conservation function recovery. [Methods] The dynamic changes in water conservation on the temporal and spatial scale in Gansu Province from 2001 to 2023 were evaluated quantitatively using the InVEST model, and the influencing factors of the water conservation function were analyzed using the geographic detector. [Results] ① The average water conservation in Gansu Province from 2001 to 2023 was 9.24 mm, and the water conservation fluctuated little during different periods. The change in water conservation was consistent with the precipitation and water yield, showing an upward and then a downward trend. ② From 2001 to 2023, the average water conservation capacity of different land use types in Gansu Province was ranked as cultivated, grass, forest, urban construction, unused land, and water area. ③ Precipitation was the most important driver for the change of water conservation in Gansu Province, and the interactions between precipitation and evapotranspiration, land use type, and elevation had the most significant influence on the spatial difference of the water conservation service function in Gansu Province. [Conclusion] The overall distribution pattern of water conservation in the Gansu Province was lower in the northwest and higher in the southeast. The change in water conservation function was mainly influenced by climate factors and human activities.